Method of protecting plants from fungi by applying hydrazine salts of inorganic phosphorous acids



United States Patent 7 2,773,796 METHOD-13F PRGTECTINGPLANTS FROM EUNGIBY APPLYING SALTS F INOR- 1 GANIC PHosPHoRoUs JACIDS JohannesTh'omasfiaekmanh and Gerarda ih'auciscaElisa Dirick, 'N'etherlands,assignors "to shell Development compahm Eiiferyville, Calif.,acorporafiono'f Delaware No Drawing. Application; septemherslfi, 195 3,Se'riailNo. 380,607

Claims pi'idrify, application eerman'y september'asflasz s cla'ims.:(Cl. 167-14 ii'iven'tion relates I to a-ineth'od of co'inha'tiir'gpests. More particularly, it relates to a method ofprotectingplants-from destruction by pests-such as-fung'i.

1: is knowh that hydrazine -(e'r hydrazine hydrate) is a toxicfriater'ial. Hoiveven thiscompoundis completely unusable for treatingplant's because of its 'eiti'e'me phy totoiiity.

It has now been found that salts-"tif hydrazineand inorganic oxygenacids of phosphorus can be employed for treating plants toprevefittheirHestruction by-pe'sts without substantialdamage totheplants.

Typical hydrazinesalts which can'be 'used in accordance with thep'resentinventionare th'e hy'draziiiesalt's "of phosphoric acid,phosphorous aaeid,.hypophosphoric acid, pyrophosphoric acid,and'the'like, wherein the salts are essentially tree 6f 'inetal:eonstitueiits. The prese'ri'tiliydrazine salts need not necessarily beneutral. The Hydrazine salts preferred are those in which the mole ratioof acid to hydrazine is from about 0.5:1 to about 2:1.

The hydrazine salts of the present invention can be prepared by anyconventional method, for example, by reacting a solution of hydrazinewith the desired acid, by reacting a solution, preferably an alcoholicsolution, of a hydrazine salt with the desired acid, or by reacting asolution, preferably an alcoholic solution, of a hydrazine salt with asalt of the desired acid.

The hydrazine salts of the present invention need not be employed in apure condition. Inactive admixtures which have been formed in thecommercial preparation of the hydrazine salts can be present.

The hydrazine salts of the invention can be used alone or in combinationwith other fungicidal, viricidal, insecticidal or acaricidal materials,the action of which may be either internal or external, with plantnutritives, with plant hormones, and the like. Wetting agents and, ifnecessary or desirable, stickers can be present. The present hydrazinesalts are preferably applied in the form of aqueous solutions orsuspensions. Aqueous solutions or suspen sions containing from about0.01 to about 1% by Weight, and preferably from about 0.1 to about 0.5%by weight, of the hydrazine salt are particulaarly suitable.

The active agents of the present invention are particularly suitable asfoliage fungicides because of their high fungitoxicity and lowphytotoxicity. However, these materials are also suitable for treatinganimals as well as inanimate materials to prevent attack thereof bypara- "salts 'of "hydrazine.

, 2,773,796 Patented Dec. 11, 1956 2 1 sites ana pests, such as fungi,insects, bacteria, and he like.

The invemi'on'is illustrated 'by the fdllowing examples which areno't'tobe considered as Iirnitin'g'the specification and claims in anymanner:

EXAMPLE Cucumber -plant's having a height of about 1'0"c'ms. werezpla'ced for four hours with their roots in various'concen't'ratio'risof solutions of the HCL'H2SO4, 'andHzPOi The cucumberplants were "then replanted. The HsPotsal'tof'hydraz'me was found twhemm -phytotexicp Both -'-the H01 and HS'Or' salts 'were theirmse'poseoficombating Vert-icillium',-, with various-concentrat tionsZOfSOlILltiOIlS'Of :hydrazine hydrate and of the HsPOe' salt -ofhydrazine by placing the plants with ilthe'ir in 'thedifferent solutionsfor a'period of' 2'4 hours. The

pIarits ewere then replanted. After a wee'k, the plants treated withhydrazinel liydrate werefde'ad, Whereas theplants treated :with theFHB'PQ'4 salt of hydrazine 'Zsliowed nodam'age F'of anykind.

:Salts of ahydrazine'zwith various oxygen acids :of tph'o'sphorus weretested on various plantsztoi-determineitheir effectivenessasfungicides.The results are given in Table 1. Their effectiveness :as vsftir gicides:is indicated intthe table as degree -:of suppression. 'I=he,=degree ofsuppressionw/as determinedvin thefollowingrnanner: I v

Test plants were sprayed with an aqueous solution of the active agentuntil the liquid dropped from the leaves. After the spray liquid dried,usually after about two days, the plants were exposed to contaminationwith the pathogen. Depending on the kind of test plant and of thefungus, contamination was effected either by inoculation of the plant orby placing the plant in contaminated surroundings, for example, in agreenhouse in which plants affected by the pathogen were present.Conditions were chosen such that the plants which were not treated withthe active agent soon became diseased. After a certain period hadelapsed, depending on the plant tested, the ratio of the affected leafsurface to the total leaf surface was determined for both the treatedand the untreated plants. The quantity obtained by subtracting thequotient of these two numbers from one is a measure for the de' gree towhich suppression of the pathogen has succeeded. This quantity,expressed in percent, is termed the degree of suppression. The degree ofsuppression was determined at a time at which the untreated plantsshowed clear symptoms of the disease. As a rule, the leaf surfaces werenot measured, but estimated with the required accuracy. An experiencedperson can in this way determine the degree of suppression with anaccuracy of about 5%. This accuracy is sufiicient since, in general,results obtained in biological tests are only reproducible within ratherwide limits.

For purposes of comparison, the degree of suppression obtained with theuse of known fungicides is also given in the table.

Table I Comparison Spraying Concenlyiol tratlon oi Acid er SprayedDegree Concen- Hydrazine Salt oi- Mo Fungus Plant Aqueous of Suptrationof Degree Hydra- Solution pression Active Substance Sprayed 01 Supzine(percent Solution pression wt.) (percent H ophosphoric acid (H,P 0e) 1Phytophthora infestans... Tomato. 0. 1 95 cupric oxychlorida 0. 75 ,28Ort ophosphoric acid (H;PO4).- 1 -.--.do ..do 0.1 93 -...do 0.75 28 Do 2.do ..do 0. 1 75 do 0.75 28 I Do 2 Septon'a araveolentis- Celery 0. 1 40ferrous dlmethyl- 0. 2 40 dtithiocarbamv a e. Phosphorous acidlfl Poa) 1Phutophthora lnfmam.-. Tomato 0.1 88 cupricoxychloride. 0.75 28 Do lSeptona graveolamfs Celery 0.1 70 ferrous dimethvl- 0.2 49

-' 7 7 dithiocarbame. Do 0. 5 Phytopllthora infestam--- 0. 1 88 cupricoxychloride- 0. 75 28 Pyrophosphoric acid (H4P1O1) 0. 5 do 0. 1 70 -.do0. 75 5 D 0.5 ..do 0.1 78 d0 0.75 ,28,

-0. 5 Corn plants- 0. 1 46 zinc bisdithiocar- 0.2 68

' bamate. 0. 5' Phytophthom lnfeatam"- Potato 0. 1 32 cupricoxychloride. 0. 75 46 0.5 Cladnsporiumfulvumuu Tomato.-- 0.1 56Salicylanilide.-. 0.6 33

;From the data in the above table, it can be seen that, in general, thehydrazine salts of the present invention are far .moreefiective at muchlower concentrations than 7 known fungicides.

We claim as our invention:

1. A method for p'rotectingplants from destruction byfungi whichcomprises applying to the plants the hydrazine salt of an inorganicphosphorus acid selected from the group consisting of phosphoric acid,phospho-l rousacid, hypophosphoric acid, and pyrophosphoric acid in anamount toxic to said fungi, said hydrazine salt having a mole ratio ofacid to hydrazine from 0.5:1 to 2:1 and being essentially free of metalconstituents.

, Z. A methodfor protecting plants from destruction by fungi whichcomprises applying to the plants the hydrazine salt of hypophosphoricacid in an amount of toxic to said fungi, said hydrazine salt having amole ratio of acid to'hydrazine from 0.5:1 to 2:1 and being essentiallyfree of metal constituents. I

3. A method for protecting plants from destruction by fungi whichcomprises applying to the plants the hydrazine salt of phosphoric acidin an. amount toxic to said fungi, said hydrazine salt having a moleratio of acid to hydrazine from 0.5 :1 to 2:1 and being essentially freeof metal constituents.

4. A method for protecting plants from. destruction by fungi whichcomprises applying to the plants the hydrazine salt of phosphorousacid'in an amount toxic to said.

fungi, said hydrazine salt having a mole ratio of acid to hydrazine from0.5:1 to 2:1 and being essentiallyifree of metal constituents. 5. Amethod for 'by fungi which comprises applying to the plants the hydrazine salt of pyrophosphoric acid in an amounttoxic. to said fungi, saidhydrazine salt having a mole ratio of, acid to hydrazine from 0.5:1 to2:1 and being essentially;

.free of metal constituents.

Ref erencesCited in thefileof this patent UNITED STATES PATENTS OTHERREFERENCES Merck Index, 5th fate.

protecting plants from destruction Soule Nov. 17, 1953.

edition, page 275, Hydrazine .Sul-l

1. A METHOD FOR PROTECTING PLANTS FROM DESTRUCTION BY FUNGI WHICHCOMPRISES APPLYING TO THE PLANTS THE HYDRAZINE SALT OF AN INORGANICPHOSPHORUS ACID SELECTED FROM THE GROUP CONSISTING OF PHOSPHORIC ACID,PHOSPHOROUS ACID, HYPOPHOSPHORIC ACID, AND PYROPHOSPHORIC ACID IN ANAMOUNT TOXIC TO SAID FUNGI, SAID HYDRAZINE SALT HAVING A MOLE RATIO OFACID TO HYDRAZINE FROM 0.5:1 TO 2:1 AND BEING ESSENTIALLY FREE OF METALCONSTITUENTS.